1. Field of Invention
This invention relates to dishwashers and in particular to an apparatus for stabilizing a dishrack during in and out movement from within a dishwasher tub wherein the dishrack is disposed.
2. Description of the Prior Art
In a typical front-loading dishwasher, there is provided an upper dishrack which is moveable in and out of the interior of the dishwasher tub in order to enable loading of dishware items into the dishrack. In a conventional form of a dishwasher, the dishrack is provided with simple support wheel assemblies disposed on opposite sides of the dishrack for rolling on a track provided on the sidewall of the dishwasher tub such that the dishrack is supported for movement in and out of the dishwasher tub. Typically, the simple support assemblies for dishracks are configured to allow a predetermined looseness or tolerance both laterally and vertically to ease manufacturing and assembly requirements. Precision mounting components could substantially eliminate such looseness but would be prohibitively expensive. This looseness, however, produces an objectionable sensation of sloppiness during the movement of the dishrack. It is desirable, therefore, to provide a means for preventing the objectionable sensation of sloppiness in moving the dishrack while permitting lateral and vertical looseness in the dishrack support assembly such that manufacturing costs are minimized.
U.S. Pat. No. 3,323,853 discloses a drawer travel guide mechanism for guiding a drawer and preventing yawing of the drawer relative to a cabinet casing when moving in and out thereof. Roller bearings, supported by U-shaped brackets, support the weight of the drawer. A torque rod is provided extending between open center portions of the roller bearings. Pinion gears are secured at either end of the torque rod for engagement with gear racks located on the underside of the drawer. During operation, the drawer moves in and out of the cabinet casing riding on the stationary roller bearings while the torsional interconnection of the pinion gears on the torque rod defeats the tendency of the drawer to skew. This mechanism, while basically achieving an anti-skew effect for a drawer, does not lend itself to a dishrack application because the bottom-mounting of the torque rod is not suitable for an upper dishrack as it would interfere with the cleaning action of the dishwasher spray. Further, the roller bearing support structure is relatively elaborate and costly and would be difficult to maintain in an interior dishwasher environment.
U.S. Pat. No. 4,226,490 discloses a stabilizing arrangement for stabilizing the in and out movement of a dishwasher dishrack including a stabilizer axle mounted to the dishrack and extending normal to the direction of movement of the dishrack. Frictional rollers are fixed at either end of the stabilizer axle, spring biased into engagement with a horizontal top interior surface of the dishwasher cabinet. The constrained simultaneous rotation of each wheel and the spring bias combine to prevent lateral skewing and vertical sloppiness. This stabilizing arrangement, however, is relatively costly and complex and includes a plurality of components in addition to the stabilizer axle and the frictional rollers. Further, this system relies on the frictional engagement of the frictional rollers and the horizontal top interior surface to prevent lateral skewing. It is contemplated by the inventors of the present invention that the presence of a water film or grease residue on the horizontal top surface of the cabinet, as commonly occurs, would substantially reduce the utility of the frictional engagement. Further, the spring bias required in the above described stabilizing arrangement may objectionably increase the force required to move the dishrack in and out of the cabinet.